Numerous procedures have been developed in modern medicine that require the percutaneous insertion of one or more interventional devices into the vascular system. Such procedures include, for example, percutaneous transluminal coronary angioplasty (PTCA), X-ray angiographic procedures, and the like.
The interventional devices intended for use in such procedures may be introduced into the vascular system by a variety of known techniques. In the widely used Seidinger technique, a surgical opening is made in a body vessel, such as an artery or vein, by a needle, and a wire guide is inserted into the body vessel through a bore in the needle. The needle is then withdrawn, leaving the wire guide in place. A dilator positioned within the lumen of an introducer device is then inserted over the wire guide and advanced into the body vessel. Once the introducer is positioned as desired within the body vessel, the dilator is withdrawn. A variety of medical devices, such as catheters, delivery systems, cardiac leads, and the like, can then be advanced through the introducer to a point of treatment in the body vessel.
In many cases, an introducer will include one or more hemostatic valve members (also referred to as check valves) for inhibiting leakage of bodily fluids, such as blood, through the introducer as an interventional device is inserted through or withdrawn from the introducer. In some cases, hemostatic valves that include an elastomeric component are used to minimize fluid leakage during these exchanges. These hemostatic valves that include an elastomeric component are dependent upon the ability of the elastomeric component to seal around the interventional devices to close any gaps created upon insertion or withdrawal of the device through the valve.
During procedures involving the percutaneous insertion of one or more interventional devices into the vascular system it is sometimes necessary or desirable to replace a previously-inserted interventional device with another interventional device of a different diameter, or even with an interventional device of a different type. Such exchanges are normally made over the wire guide, wherein the old device is withdrawn over the wire guide and the new device is inserted into the body vessel over the existing wire guide or a newly-inserted wire guide. In addition procedures, such as the placement of endovascular grafts, can involve interventional devices of relatively large diameters and/or simultaneous placement of multiple interventional devices through the introducer. These procedures present challenges in the efforts to inhibit leakage as conventional hemostatic valve members are not well-suited for such procedures. Thus, there is a need for improved hemostatic valves and medical devices that include such valves.